Thyroid disease is caused by over- or underproduction of thyroid hormones. An overproduction of thyroid hormones is called hyperthyroidism, and an underproduction of thyroid hormones is called hypothyroidism.
These conditions can occur because of problems such as inflammation of the thyroid, nodules that develop on the thyroid gland, autoimmune disorders, and exposure to radiation.
Causes of Hyperthyroidism
Hyperthyroidism occurs when the thyroid overproduces thyroid hormones. This can happen due to inflammation in the thyroid, called thyroiditis, which causes the thyroid to create excess hormones.
Hyperthyroidism can also be caused by nodules that are known as toxic adenomas, which develop on the gland and start secreting hormones in addition to the hormones produced by the thyroid.
In rare cases, hyperthyroidism can be caused by a pituitary gland dysfunction or cancerous growth on the thyroid that can disrupt the hormonal balance and production of T3 and T4.
Autoimmune disorders such as Graves' disease can also cause hyperthyroidism.
What Is the Thyroid?
The thyroid is a butterfly-shaped gland in the front of the neck. Its primary function is to produce the hormones triiodothyronine (T3) and thyroxine (T4). These hormones travel through the body and help regulate metabolism. They also aid in brain development, digestive function, muscle control, and balancing mood.
Causes of Hypothyroidism
Hypothyroidism and the diseases associated with it happen when the thyroid doesn't produce enough thyroid hormone, which also results in a lack of energy. Causes of hypothyroidism include an autoimmune disorder such as Hashimoto’s disease. This is a condition in which the body attacks the thyroid and causes it to produce fewer thyroid hormones.
Hypothyroidism can also be a result of exposure to high amounts of radioactive iodine from hyperthyroidism treatment, which then results in permanent hypothyroidism.
Hypothyroidism could also be a side effect of radiation therapy used to treat cancers in the head and neck. Pregnancy can also cause hypothyroidism, as well as a congenital defect from birth in which the thyroid does not develop properly.
What Is Autoimmune Thyroid Disease?
With an autoimmune thyroid disease, your system mistakenly attacks your thyroid, a gland that produces hormones that control a variety of bodily systems and functions. The two common types of autoimmune thyroid disease are Hashimoto’s thyroiditis, which results in too little hormone, and Graves’ disease, which results in an overproduction of hormone.
Risk Factors
Some people are at higher risk of developing thyroid problems than others. Your risk can be affected by things like genetics, your gender, and your lifestyle habits.
Genetics
Conditions like Hashimoto’s disease and Graves' disease can be hereditary. Aside from family history, there are several other risk factors for both hypothyroidism and hyperthyroidism, some of which (including gender and pregnancy) overlap.
Age and gender (women over 60 at high risk)
Preexisting condition (autoimmune disease such as type 1 diabetes or celiac)
Pituitary gland disorder
Pregnancy (women who are pregnant or who have had a baby in the past six months at high risk)
Gender (females at higher risk)
Family or personal history of autoimmune disorders (celiac, lupus, rheumatoid arthritis)
Past trauma to thyroid gland
Current or recent pregnancy
Smoking
Recent use of iodine contrast (such as that used in CT scans)
Gender
Thyroid diseases are often caused by autoimmune diseases, which are more common among females. In addition, the female hormone estrogen increases the production of thyroid-binding globulin, which will increase thyroid hormone requirements in patients who are on thyroid hormone treatment. As a result, problems often arise when estrogen balance changes, such as in pregnancy or menopause.
Can stress trigger thyroid problems?
It is unclear whether stress can cause thyroid problems, though it can worsen symptoms.
Lifestyle Risk Factors
There are certain lifestyle factors that increase the risk of thyroid disorders. They include:
- Smoking, as tobacco contains substances that affect the thyroid gland, causing inflammation and interfering with the absorption of iodine as well as the production of thyroid hormones
- Injury or trauma to the thyroid
- History of certain medication use in high amounts, such as lithium (used in many mood stabilizers)
One of the biggest hurdles in diagnosing thyroid disease is that its symptoms are common among many different types of diseases. One of the most important steps to take if you think you might have an issue with your thyroid is to get blood work done. This will show the levels of thyroid hormones in your bloodstream and could be an important step to properly diagnosing and treating your condition.
Summary
Hyperthyroidism can be caused by inflammation of the thyroid or other conditions like toxic adenomas, pituitary gland dysfunction, or cancer. Hypothyroidism can happen as a side effect of exposure to radioactive iodine or radiation therapy.
Several autoimmune conditions such as Grave's disease and Hashimoto's disease can also cause problems with the thyroid gland.